This work will continue the main research theme of our laboratory, namely, the molecular mechanism of iron assimilation in microorganisms. The specific project to be pursued will be the aerobactin transport system in selected strains of enteric bacteria. The preliminary evidence that plasmids are involved in aerobactin synthesis and utilization in enteric bacteria will be confirmed or rejected. The plasmids observed in Aerobacter aerogenes 62-1 and in Arizona hinshawii will be eliminated and the cured strains examined for aerobactin production. Efforts will be continued to locate plasmids in Salmonella memphis. The putative membrane receptor for ferric enterbactin will be identified on gels and attempts will be made to isolate and characterize this membrane protein.